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' C,eolagical Tecknles frit. Page 4 Sinclair Trucking Feasibility Study Addendum Project No. 1030.3 April 26,2004 ' ORCs are magnesium peroxide compounds that slowly releases oxygen once it is hydrated. The byproducts of the reaction are oxygen and magnesium hydroxide. The material continues to release oxygen in the subsurface for approximately 6 months after application. ' The ORCs are installed using a GeoProbe direct push rig and a pressure pump. A series of borings are pushed to a detennined depth then a slurry of ORC is pumped through the drill rods under pressure as the rods are retrieved from the boring. The borings are drilled in a ' grid,pattern in the area of highest groundwater contamination. The application and cost of ORC and an AOP are very similar, however the AOP has the ' advantage because it is directly breaking down the contaminant where the ORC is only increasing oxygen to aid in bioremediation. Bioremediation is a relatively slow process that can be dependent on site conditions other then just oxygen levels. ' Site-specific Limitation It would seem that in situ remedial methods would be ideal, since the septic tank and leach line system would not have to be disturbed and the issue with fine grained soils and shallow groundwater could easily be dealt with. Site-specific Concern ' What is the potential effect of in situ ozone treatment for contaminated groundwater remediation on trees grown in close proximity to the treatment site? The potential effect of ozone gas in the vadose zone on trees, grasses, and other vegetative structures has not been well studied. However, certain assumptions can be made based on data produced from the field of phytoremediation and from agricultural studies, which have used ozone for plant treatment. The roots of trees are mostly concentrated in the upper 0.5- 1.5 ft of the surrounding soil, where the most oxygen and nutrients are found. The outer covering of the root contains mycorrhizae associated fungi, which are beneficial to the nutrition of the tree. Negative impacts of ozone gas in the vadose zone would most likely ' be due to the disinfecting properties of the ozone gas on root-associated fungi rather than on the tree root. Fairly high levels of ozone are required to disinfect fungi, and dosages of around 10-12 mgll are typical when using ozone to treat fungal contamination. ' Breakthrough levels of ozone at these levels have not been detected during in-situ remediation trials using high flows of pressurized ozone (personal communication, Chuck Whisman, Geological and Environmental Services, Exton, PA). In addition, a ' comprehensive study by the California Energy Commission (CEC) entitled "Integrated Agricultural Technology Demonstration", .Tune 1999, demonstrated the effect of using ozone gas in place of standard chemical treatments for bacterial and viral pathogens on ' agricultural crops. During these trials, the CEC showed that plants treated with 6% ozone gas, or with ozonated water, demonstrated increased plant yield and vigor. While this was partly due to the removal of the plant pathogens, the application of ozone as a treatment regime greatly enhanced the oxygen concentration in the irrigation water and soil. Treatment of contaminated groundwater with ozone would likely have the same positive effect on trees and other vegetation that are in proximity to the in-situ treatment site, due to the release of oxygen into the vadose zone during ozone treatment of the aquifer.